Observe the perigee full Moon on 8 February 2020

A perigee full Moon will be visible on the night of 8 February 2020 into the morning of 9 February.

A perigee full Moon (left) appears 30% brighter and 14% larger than an apogee full Moon (right). Credit: Pete Lawrence

A perigee full Moon will be visible on the night of 8 February 2020, but what is meant by perigee and apogee Moons?

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The lunar orbit is elliptical, meaning the Moon’s physical distance from Earth is constantly changing.

The two orbital extremes are known as perigee (closest to Earth) and apogee (farthest from Earth) and each occurs once a month.

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The timing of full Moon and lunar perigee or apogee are not in sync but drift in and out of phase over the course of many lunar orbits.

During certain months, full Moon occurs closer to perigee than others. Once one occurs, the next two will typically be close to perigee too.

The first of these ‘supermoons’ for 2020 occurs on 9 February. On this occasion full Moon is at 07:34 UT, with lunar perigee on 10 February at 20:32 UT.

Next month full Moon occurs on 9 March at 17:48 UT, with perigee on 10 March at 06:34 UT.

Finally, in April full Moon occurs on 8 April at 03:36 BST and perigee on 7 April at 18:10 UT.

The visual impact of a perigee full Moon compared to an apogee full Moon is that the full Moon appears approximately 30 per cent brighter and 14 per cent larger.

However, in reality, as previous and subsequent full Moons to the perigee full Moon are near to perigee themselves, the difference from one month to the next is barely noticeable.

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Pete Lawrence is an experienced astronomer and  co-host of The Sky at Night. This article originally appeared in the February 2020 issue of BBC Sky at Night Magazine.